Fig 1. Oxidative stress in cancer cells under cycling hypoxic conditions.

Oxidative stress is a state of redox imbalance caused by the increased production of reactive oxygen species (ROS), which are mostly generated by the leakage of excessive levels of electrons relative to O₂ in impaired mitochondrial respiratory chains. ROS damage proteins and DNA/RNA and also act as signaling molecules to drive cancer cell motility/invasion and tumor progression. ROS (superoxide anion: O₂-, hydrogen radical: HO., hydrogen peroxide: H₂O₂)